Former U.S. president Jimmy Carter will speak to the Cuban people later Monday n an unprecedented national broadcast in which he is expected to emphasize human rights and democracy. Mr. Carter has already given encouragement to the pro-democracy movement in Cuba with his presence.

In small ways former President Carter has already provided a preview to what he is likely to say in his speech to the Cuban nation. In his public appearances here in Cuba he has spoken of democracy and human rights and on Monday he had breakfast with two well-known advocates of political change.

One of those men, Elizardo Sanchez, president of the Cuban Human Rights Commission, says he is very hopeful that the former president's visit will bring about a change. He says he is impressed by the goodwill Mr. Carter has shown and he hopes that this visit may help improve relations between Washington and Havana.

Mr. Sanchez is one of the advocates of a democratic opening in Cuba represented by a petition delivered to the National Assembly last week seeking a referendum on such issues as free multiparty elections, freedom of speech and amnesty for political prisoners.

These issues came up Monday evening during a visit to Cuba's Latin American Medical School, where Mr. Carter spoke of the advantages of democracy. He said citizens in a democracy cherish the right to criticize their own government and to change it through elections. But Cuban President Fidel Castro, who was also present, gave a different view of democracy, noting that when it began in ancient Athens, it consisted of 20,000 citizens participating in self-government while ruling over 50,000 non-citizens and 80,000 slaves. He said this situation continues today as people in rich nations participate in democracy while most of the world's people live in poverty.

In another development, the Cuban government on Tuesday issued a statement expressing gratitude to U.S. Secretary of State Colin Powell for statements he made Monday regarding biotechnology research in Cuba. Mr. Powell said Cuba has the capacity and capability to conduct bio-weapons research, but does not necessarily have any biological weapons. Last week, Undersecretary of State John Bolton had said that Cuba had "at least a limited biological warfare research and development effort." He also accused the Castro government of sharing this technology with other so-called rogue states.

On Monday, Jimmy Carter addressed the issue while visiting Cuba's biotechnology research center, saying that American officials had told him Cuba had no such weapons and that Cuba had not given any assistance to other countries that could be used for terrorism. He also said anyone who had such suspicions should take advantage of an offer made by Mr. Castro and come to Cuba to investigate the matter.